Embodiments of the present invention relate generally to a method of manufacturing semiconductor devices, and more particularly, to a method of manufacturing semiconductor devices to remove an unwanted defect in patterned cavities known as “grass.”
During deep reactive ion etching (DRIE) processing, a defect known as “grass” is known to occur. “Grass” refers to thin spikes of silicon or other semiconductor material remaining after the etch process. An example of this defect is shown in FIG. 13. In most cases, the chemistry of the etching process can be adjusted to remove the occurrence of “grass.” However, in some circumstances, the etch chemistry cannot be adjusted to eliminate this defect.
For example, in applications requiring a double etch, i.e., a pattern formation in a semiconductor layer followed by formation of cavity such that the pattern becomes recessed in the cavity, the process itself appears to cause heavy grass formation. Accordingly, it is desired to provide a process solution to remove unwanted “grass” defects during double etch procedures.